• A. Peters, E. Feldmeier, R. Steiner
  HIT, Heidelberg
• H. Eickhoff, T. Knapp, C.P. Welsch
  GSI, Darmstadt
• C. Schömers
  MPI-K, Heidelberg

The use of hadron beams delivered by normal conducting synchrotrons is highly attractive in various fundamental research applications as well as in the field of particle therapy. These applications require fast synchrotron operation modes with pulse-to-pulse energy variation and magnetic field slopes up to 10 T/s. The aims are to optimize the duty-cycle or to minimize treatment times for the patients as well as to provide extremely stable properties of the extracted beams, i.e. position and spill structure. Studies performed at the SIS18 synchrotron at GSI showed that not only the dipoles but the quadrupoles as well significantly contribute to the underlying time constants of the slowly extracted beam. An attempt has been made to measure the magnetic fields in synchrotron magnets with high precision and speed comparable to the current measurement with a DCCT. Additional magnetic field monitoring includes the retarding effects into the current control feedback loop neglecting the unfavourable dynamic effects from hysteresis and eddy currents. The presentation describes this controls approach, the results obtained at the HIT synchrotron and the SIS18 at GSI will be discussed.

• F. Nürnberg, B.G. Logan
  LBNL, Berkeley, California
• I. Alber, K. Harres, M. Roth, M. Schollmeier
  TU Darmstadt, Darmstadt
• W.A. Barth, H. Eickhoff, I. Hofmann
  GSI, Darmstadt
• A. Friedman, D.P. Grote
  LLNL, Livermore, California

Ion acceleration from high-intensity, short-pulse laser irradiated thin foils has attracted much attention during the past decade. The emitted ion and, in particular, proton pulses contain large particle numbers (exceeding a trillion particles) with energies in the multi-MeV range and are tightly confined in time (< ps) and space (source radius a few micrometers). The generation of these high-current beams is a promising new area of research and has motivated pursuit of applications such as tabletop proton sources or pre-accelerators. Requirements for an injector are controllability, reproducibility and a narrow (quasi-monoenergetic) energy. However, the source provides a divergent beam with an exponential energy spectrum that exhibits a sharp cutoff at its maximum energy. The laser and plasma physics group of the TU Darmstadt, in collaboration with GSI and LBNL, is studying possibilities for transport and RF capture in conventional accelerator structures. First results on controlling laser-accelerated proton beams are presented, supported by WARP simulations.

• W.A. Barth, L.A. Dahl, H. Eickhoff, L. Groening
  GSI, Darmstadt

The GSI UNILAC serving as a high duty factor heavy ion linac is in operation since nearly 35 years. An upgrade program dedicated to FAIR will be finished until 2011. For the FAIR project the synchrotron SIS 18 has to be filled up to the space charge limit. After re-commissioning of the UNILAC the replacement of the main DTL is foreseen. A new 4 MV/m 108 MHz IH-LINAC provides a high intensity 5 MeV/u U⁴⁺-beam. The existing gas stripper section is reused to perform a beam intensity of 24 emA in charge state 42+. The existing UNLAC-tunnel may house a high efficient linac structure. A superconducting or normal conducting 324 MHz-CH-linac (crossbar H-structure) is under consideration as well as rf-resonators of half wave or quarter wave type. The new high energy linac should be able to boost the beam energy up to 30 MeV/u. A further upgrade option is a second 100 m-linac (324 MHz) to enhance the beam energy to up to 100 MeV/u (U⁴¹⁺), sufficient to feed the FAIR 100 Tm synchrotron in direct line. The paper will report on the ongoing conceptual layout of a new UNILAC-concept.